Smoke is not appearing in Cycles render
Your problem is that you have not specified any attributes for the two attribute nodes to access.  The one controlling the scatter and adsorption should be using the density, this means that the fac output will be carrying the density voxel (volume-pixel) data of the smoke simulation.  Similarly the node controlling the emission shader should be using the flame attribute (I presume that the emission shader is for the flames).

Like this: